1. Field of Invention
The present invention relates to the art of coating concrete or metal surfaces to resist corrosion, and more particularly to the application of polymer layers to surfaces to prevent pin holes and other corrosion enhancing conditions against corrosive liquids and materials.
2. Description of the Prior Art
In the past it has been known to coat the inner surfaces of water or sewer pipes and reservoirs in order to retard the disintegration of the pipe and reservoir walls. Such pipes and reservoirs frequently are made of concrete, but often can be made with metal liners and metal parts. Fluid flowing through such pipes and into such reservoirs contain highly corrosive material, both caustic and acidic which ultimately has a deteriorating effect on the pipes and reservoir walls.
It has been suggested before to use coatings and liners for protecting such pipes and walls. Such coatings and liners frequently were made of various forms of plastic and epoxy materials. When such epoxy materials were applied to water system pipes and reservoirs, small pin holes or "blow holes," as they are frequently called, remain in the coating upon settling or curing. Over a period of time, the caustic in the fluid will seep through such pin holes or blow holes and slowly corrode the concrete or metal which is supposed to be protected.
On the other hand, polyethylene strips and similar type plastic strips have been applied to the surfaces of such pipes and reservoirs. Such strips were fastened to the surfaces by various mechanical lockings, such as, for example, "T" locks, bolts, screws and like fastening arrangements. While such locking arrangements operate to keep the polyethylene or other type of plastic strips in proximity to the pipe or reservoir wall surface, the corrosive fluids oftentimes seeped through the cracks created by the locking arrangements themselves to corrode the wall substrate and migrate laterally from the fastening seam or hole to further deteriorate, eventually, the entire substrate. In addition, the bolt and screw fastening arrangements actually protrude into the wall substrate to cause further deterioration or weakening.
It is known that polyethylene strips are good lining material for containing acidic fluids. In transporting such corrosive fluids, bladder-type liners insertable into the transportion means, such as, for example, containment holding tanks, have been used. Such liners, however, require structural support. In some instances, extremely thick plastic liners must be employed. Such plastic liners, however, have never been adhered to the wall or pipe throughout the surface area of coverage by a self sufficient protective coating.
Moreover, any pin hole or other break or penetration through the liner will normally contaminate and corrode the entire substrate.
It has long been sought to provide a method for bonding a polyethylene or a polyvinyl chloride material coating to the entire surface area of a pipe or reservoir so as to provide a complete coating and liner barrier which is free of pin holes or blow holes, and without the conventional method of mechanically fastening or locking such polyethylene sheets onto the surface. It has also long been sought to fasten a polyethylene or polyvinal chloride lining to an entire substrate by means of a bonding agent which itself provides additional protection to the substrate, such as polyurethane.